α-Gel has a hydrate-type crystal structure, which is a lamellar structure. The intercorneocytic lipid present in the horny layer (i.e., the outermost skin layer) generally has the α-gel structure. The intercorneocytic lipid prevents entry of outside substances into the skin as well as transepidermal water loss, and the intercorneocytic lipid itself retains water, whereby the softness and smooth appearance of the skin can be maintained. In the skin, the horny layer retains approximately 33% water in the form of bound water, and the intercorneocytic lipid has been reported to retain approximately 13% bound water (the bound water as stated herein is defined as water constrained by components) (Non Patent Literature 1).
Patent Literature 1 discloses an emulsified composition comprising a ceramide known as an intercorneocytic lipid, and the like. Patent Literature 1 states that an emulsified composition having a high moisturizing effect can be obtained by dispersing a ceramide which forms a lamellar α-gel structure into water. This is intended to allow an easily crystallizable ceramide to have the α-gel structure to thereby enhance flowability and skin penetration.
Meanwhile, Patent Literature 2 discloses a cosmetic composition comprising combination of moisture rich compounds, including a low-molecular-weight compound such as an amino acid and a high-molecular-weight compound such as hyaluronic acid.